Presently, there is a need for autonomous, portable, hand-held chemical analysis systems for the rapid and sensitive detection of particular chemicals including pollutants, high explosives and chemical warfare agents. Such miniaturized chemical analysis systems, which have been termed "chemical laboratories on a chip", are currently being developed based on gas chromatography. The requirements for these chemical analysis systems are that they provide a high chemical selectivity to discriminate against potential background interferents which may be present at up to a thousand-fold or more higher concentration, that the chemical analysis be performed on a short time scale (e.g. in a minute or less) and that the chemical analysis be performed with high sensitivity (e.g. at concentrations down to the part-per-billion level). Low electrical power consumption is also needed for field use over a prolonged time period.
The present invention is of a millimeter-sized chemical preconcentrator which can be used with the above miniaturized chemical analysis systems to increase the sensitivity and selectivity with which chemical analysis measurements can be made.
An advantage of the chemical preconcentrator of the present invention is that it can be integrated with other elements of a chemical analysis system in a hybrid or monolithic fashion to provide a substantial improvement in the detectivity of particular chemical species of interest.
A further advantage of the present invention is that a sorptive coating of the chemical preconcentrator can be tailored for chemical selectivity to one or more chemical species of interest and thereby accumulate and concentrate these chemical species from an ambient or sample vapor over time while being relatively insensitive to other chemical species not of interest.
Yet another advantage of the present invention is that the accumulated chemical species of interest can be concentrated in a small area and subsequently released suddenly by thermal desorption to form a sample plug having a narrow temporal width and a relatively high concentration of the chemical species of interest, thereby improving the detectability of each chemical species of interest using the chemical analysis system.
Still another advantage of the chemical preconcentrator of the present invention is that it has a very small heat capacity to allow rapid heating and release of the concentrated chemical species of interest on a time scale of a fraction of a second.
A further advantage of the chemical preconcentrator of the present invention is that it is applicable to different types of chemical analysis systems, including systems based on gas chromatography and systems based on mass spectrometry.
These and other advantages of the present invention will become evident to those skilled in the art.